Device for pressing a side wall in installation for continuous casting of metal strips between two drums against the planar surfaces of the drums

ABSTRACT

The invention concerns a device for pressing a side wall ( 1 ) of an installation for continuous casting of metal strips between two cooling drums with horizontal axes against the planar surfaces of the cylinders, comprising three thrust member connected to a mounting frame ( 3 ) maintained in a fixed position, exerting their action on the rear face of a plate ( 2 ) on the front face whereof is fixed the side wall ( 1 ) or on the rear face of the side wall ( 1 ), said action being oriented along a substantially horizontal direction (Oy) parallel to the axes of the drums and being exerted via means connecting each of said thrust members on said plate. Said connection means of a first thrust member enable a relative displacement in translation of said thrust A-4 member and of the plate ( 2 ) or of the side wall ( 1 ) being along a horizontal direction (Ox) a=parallel to the plane of the planar surfaces of the drums and along a vertical direction (Oz) parallel to the plane of the planar surfaces of the drums. Said connection means of a second thrust member enable a relative displacement in translation of said thrust member and of the plate ( 2 ) or of the side wall ( 1 ) along-a horizontal direction (Ox) parallel to the plane of the planar surfaces of the drums. Said connection means of a third thrust member do not enable any relative displacement in translation of said thrust member and the plate ( 2 ) or of the side wall ( 1 ).

The invention relates to the continuous casting of metals. Morespecifically, it relates to casters for casting thin metal stripdirectly from liquid metal, of the type called “twin-roll casters”.

These casters comprise, in the usual manner, two rolls having horizontalaxes, the cylindrical lateral surfaces of which are placed side by sideat a minimum distance corresponding to the thickness of the strip thatit is desired to obtain. They thus define a casting space which isclosed off laterally by two plates made of refractory material, called“side walls”, mounted on a rigid metal baseplate and applied against theplane ends of the rolls. The peripheral surfaces of the rolls are madeof a material having a high thermal conductivity (such as copper andcopper alloys) and are internally cooled in a vigorous manner.

Each of these side walls is held in position by means of an assemblygenerally comprising a plurality of members which press it against therolls with a force at least sufficient to prevent liquid metal fromexfiltrating from the casting space. These members are mounted on aframe and comprise rigid rods which are fastened to the rear face of thebaseplate to which the side wall is fastened and which are mounted onthrust springs, or controlled cylinders, or a combination ofspring-loaded rods and controlled cylinders. These thrust members are,for example, three in number, distributed in the following manner. Oneof them exerts its action in the longitudinal mid-plane of the side walland in its lower part, at a level close to the nip, that is to say theregion where the rolls are closest together. The other two thrustmembers exert their action in the upper part of the side wall, atsymmetrical points with respect to its longitudinal mid-plane. Thethrust forces are thus distributed over the side wall so that a pressuresufficient to prevent exfiltration of liquid metal from the castingspace can be exerted on all the regions of contact between the side walland the ends of the rolls. However, this pressure must not be too highfor fear of causing rapid wear of those parts of the side wall which rubagainst the rolls, which would severely limit the duration of thecasting run. Documents JP-A-04322849 and EP-A1-0698433 arerepresentative of this prior art. The thrust members and their means ofconnection to the frame and to the side wall are all identical thereto.

Because of the high temperature of the liquid metal (about 1500 to 1550°C. in the case of steel), the members for supporting the side walls aresubjected to intense thermal stresses. It is therefore necessary to coolat least the baseplate, by means of an internal circulation of water, soas to limit the deformations and expansions of the support members.However, it is not possible to completely eliminate the expansions, andexperience shows that even minute expansions can disturb the operationof the thrust members. This is particularly so when these thrust membersconsist of controlled cylinders which are more rigid than spring-loadedrods and therefore less able to damp the variations in the position ofthe points on the side wall against which their forces are mainlyexerted. These expansions that the thrust members must absorb canfalsify the information that they receive and the actions that theytransmit to the side wall, or may even contribute to damaging them.

The object of the invention is to propose a design of a device forholding and applying the side walls against the end faces of the rolls,allowing the thrust members to exert their action without this beingdisturbed by the differential expansions of those parts of the devicethat are exposed to a high temperature.

For this purpose, the subject of the invention is a device for applyinga side wall of a caster for the continuous casting of thin metal stripbetween two rotating cooled rolls having horizontal axes against theplane faces of the rolls, of the type comprising three thrust membersconnected to a frame held in a fixed position, which exert their actionson the rear face of a baseplate to the front face of which the side wallis fastened or on the rear of the side wall, the said action beingexerted via means for connecting each of the said thrust members to thesaid baseplate or to the side wall, characterized in that the said meansfor connecting a first thrust member allow translational relativemovement between the said thrust member and the baseplate or the sidewall both in a horizontal direction parallel to the plane of the planefaces of the rolls and in a vertical direction parallel to the plane ofthe plane faces of the rolls, in that the said means for connecting asecond thrust member allow translational relative movement between thesaid thrust member and the baseplate or the side wall in a horizontaldirection parallel to the plane of the plane faces of the rolls and inthat the said means for connecting the third thrust member allow notranslational relative movement between the said thrust member and thebaseplate or the side wall.

Preferably, the first thrust member exerts its action on the lower partof the baseplate or of the side wall, while the second and third thrustmembers exert their actions on the upper part of the baseplate or of theside wall.

As will have been understood, the invention consists in connecting thebaseplate supporting the side wall (or the side wall itself if nobaseplate is used to support it) to the three thrust members whileallowing two of the three connections the possibility of moving in aplane parallel to the plane of the plane faces of the rolls againstwhich the side wall is applied, from a point kept fixed. In this way,the baseplate or the side wall can expand freely without this expansiondisturbing the actions of the thrust members, and good rigidity of thelinkages between the various parts of the side wall and its supportmeans is maintained. In particular, the action of the lower cylinder ismade independent of those of the two upper cylinders and the actions ofthe two upper cylinders are made independent of each other.

The invention will be more clearly understood on reading the descriptionwhich follows, given with reference to the single appended figure, whichshows schematically, seen in perspective, an example of a device forapplying a twin-roll caster side wall according to the invention.

The side wall 1 made of refractory material is fastened to a metalbaseplate 2 and applied against the plane ends of the casting rolls (theoutlines 3′, 3″ of which are shown by the dashed lines) by the devicewhich will be described below. The side wall 1 and the baseplate 2 areillustrated very schematically, the precise way in which they areconstructed being of no importance to the invention. The rest of thedescription will be given with reference to a coordinate system Oxyz inwhich the directions Ox and Oz are respectively the horizontal andvertical directions lying in the plane defined by the plane faces of therolls or by the side wall 1 and the direction Oy is the horizontaldirection perpendicular to the said plane, and therefore parallel to theaxes of the rolls.

The device for applying the side wall 1 according to the inventioncomprises a fixed frame 3. This frame 3 is mounted on a movable trolley(not illustrated) which allows it to be moved, as required, closer to orfurther away from the rolls, when positioning the side wall 1 before thestart of the casting run and removing the side wall 1 after the end ofthe casting run. The frame 3 and the baseplate 2 are connected by meansof three controlled cylinders 4, 5, 6. The first cylinder 4 exerts itsaction in the longitudinal mid-plane of the side wall 1 and in its lowerpart, at a level close to that of the nip 7. The second cylinder 5 andthe third cylinder 6 exert their actions in the upper part of the sidewall 1, at symmetrical points with respect to its longitudinalmid-plane, to the left and to the right of the said plane, (in theexample illustrated). These cylinders 4, 5, 6 are controlled, in a knownmanner, by a device (not illustrated) comprising computing means whichgovern the movements of their respective movable rods, so as to movethem closer to or further away from the rolls, and the forces applied tothe same rods. As is conventional, the cylinders 4, 5, 6 may becontrolled in accordance with the intensity of the forces absorbed bythe said movable rods 8, 9, 10 during application of the side wall 1against the rolls, by means of the information gathered by sensorsdesigned for this purpose.

According to the invention, the connection devices between the frame 3,the cylinders 4, 5, 6 and the baseplate 2 are constructed so as to allowthe various members involved various degrees of freedom.

The first cylinder 4 is connected to the frame 3 via a fixed rod 11.This is articulated to the frame 3 by means of a ball joint 12 whichallows the fixed rod 11 to rotate freely about its point of connectionto the frame 3 in all directions in space. The movable rod 8 of thefirst cylinder 4 is connected directly to the baseplate 2, and thisconnection is also made by means of a ball joint 13 which allows themovable rod 8 to rotate freely about its point of connection 14 to thebaseplate 2 in all directions in space. The result of this articulationof the linkage between the baseplate 2 and the frame 3 is that theconnection point 14 can move freely in space in the directions Ox andOz, especially according to the expansions and deformations of thebaseplate 2, without this disturbing the operation of the first cylinder4. In particular, the forces absorbed by the movable rod 8 will alwaysbe directed along its longitudinal axis. Should the connection point 14move, it would simply be necessary for the device for controlling thefirst cylinder 4 to make the movable rod 8 move forwards or backwards soas to control the position of the connection point 14 on the Oy axis.The control point for maintaining the force absorbed by the movable rod8 at a constant value makes it possible for this forward movement orthis backward movement to be carried out automatically withoutadditional special conditions with respect to the known control devices.

The second cylinder 5 is connected to the frame 3 via a fixed rod 15.The latter is articulated to the frame 3 by means of a ball joint 16which allows the fixed rod 15 to rotate freely about its point ofconnection to the frame 3 in all directions in space. The end of themovable rod 9 is itself connected to one end of a rigid rod 17 via aball joint 18. The rigid rod 17 slides in a slideway 19 fastened to theframe 3. This slideway 19 has the function of allowing the rod 17 tomove only in the direction Oy. The other end of the rigid rod 17 isfastened to one end of another rigid rod 20 by means of a ball joint 21.The other end of this rigid rod 20 is inserted into a slideway 22fastened to the baseplate 2 and oriented horizontally in the directionOx. Its function is to allow relative movement between the baseplate 2and the rigid rod 20 in the direction Ox and only in this direction,especially according to the expansions and deformations of the baseplate2.

The third cylinder 6 is connected to the frame 3 via a fixed rod 23. Thelatter is articulated to the frame 3 by means of a ball joint 24 whichallows the fixed rod 23 to rotate freely about its point of connectionto the frame 3 in all directions in space. The end of the movable rod 10is itself connected to one end of a rigid rod 25 via a ball joint 26.The rigid rod 25 slides in a slideway 27 fastened to the frame 3. Thefunction of this slideway 27 is to allow the rigid rod 25 to move onlyin the direction Oy. The other end of the rigid rod 25 is connected tothe baseplate 2 via a ball joint 28. The latter allows the rod 25 torotate freely about its point of connection to the baseplate 2, butprevents it from any translational mode of movement with respect to thebaseplate 2. Consequently, for a given position of the movable rods 8,9, 10 of the cylinders 4, 5, 6, the latter connection point constitutesthe only point on the baseplate 2 which is constantly kept fixed inspace. Because of the possibilities of movement which are presented tothem by the various ball joints and slideways of the holding device, allthe other points on the baseplate 2 can move freely in the Oxz plane,according to the expansions of the baseplate 2. As regards the movementsand deformations of the side wall 1/baseplate 2 assembly having acomponent along Oy, these are absorbed or compensated for by movementsof the movable rods 8, 9, 10 of the cylinders 4, 5, 6.

The reason for the invention is the fact that the possibilities of freemovement in the various dimensions in space given to the various pointson the baseplate 2 influence the behaviour of the three cylinders 4, 5,6 in an independent manner. The lower cylinder 4 is not automaticallyinfluenced by the variations in the actions exerted by the uppercylinders 5, 6, and vice versa. Likewise, the left upper cylinder 5 isnot automatically influenced by the variations in the actions exerted bythe right upper cylinder 6, particularly in the case of expansions alongOx. The configuration of the invention makes it possible to achieveisostatism of the system formed by, on the one hand, the side wall 1 andits baseplate 2 and, on the other hand, its application device.

As a variant, the ball joints 12, 16, 24 via which the cylinders 4, 5, 6are connected to the frame 3 may be mounted not directly on the saidframe 3 but separated from it by spring-loaded devices which allow thecorresponding cylinder to move backwards. This additional possibility ofabsorbing the variations in the position of the side wall 1 along Oyintroduces a degree of flexibility in the operation of the applicationdevice in that it makes it possible to react more quickly to suddenstresses due, for example, to the infiltration of solidified metalbetween a roll and the side wall 1.

The ball joints 16, 18, 24 and 26 which flank the upper cylinders 5, 6are, in principle, not absolutely essential for implementation of theinvention since, because of the presence of the slideways 19, 27, thestresses that are exerted on the movable rods 9, 10 of the cylinders 5,6 are directed only along Oy, as are the stresses that are exerted onthe fixed rods 15, 23 which connect the cylinders 5, 6 to the frame 3.It would not be outside the scope of the invention for the rods 9 and 17on the one hand, and the rods 10 and 25 on the other, to merge, andlikewise for the ball joints 16 and 24 via which the cylinders 5, 6 areconnected to the frame 3 to be omitted, this connection then becomingquite rigid. However, the presence of the ball joints 16, 18, 24 and 26provides an additional safety factor by limiting the possibility of thecylinders 5, 6 being damaged and by making their operation reliableshould the caster deform slightly due to the effect of high temperaturesof its environment.

The controlled cylinders 4, 5, 6 may also be replaced by spring-loadeddevices operating freely, without being externally slaved or controlled.The position of the side wall 1 along Oy can then be controlled by theoperator merely with the aid of means for positioning the frame 3.

Further modifications may be made to the caster as described. Inparticular, it would be conceivable to omit the baseplate 2 and connectthe thrust members directly to the rear of the side wall 1, as long asthe latter had sufficient mechanical strength and rigidity at hightemperature for this. Moreover, it is conceivable to place theconnection means of the first thrust member (those having degrees offreedom along Ox and Oz) not at the bottom of the side wall 1, asdescribed and illustrated previously, but in its upper part, bytherefore exchanging their position with one, chosen at will, of theconnection means of the second and third thrust members. Theconfiguration described and illustrated is, however, preferable sinceplacing the connection allowing movements along Oz on the axis ofsymmetry of the caster results in more satisfactory operation of thedevice. Furthermore, this makes the caster ergonomically correct since,when mounting the baseplate, it easy to start by fitting it to the twofixed connections at the top as these are easily and simultaneouslyaccessible, and then connecting the lower thrust member to thebaseplate, and to carry out the reverse operation when dismantling thesystem.

The invention applies to twin-roll casters for all types of thin metalstrip, for example strips made of steel, stainless steel and otherferrous alloys or of copper.

What is claimed is:
 1. Device for applying a side wall (1) of a casterfor the continuous casting of thin metal strip between two rotatingcooled rolls having horizontal axes against plane faces of the rolls, ofa type comprising three thrust members connected to a frame (3) held ina fixed position, which exert their actions on a rear face of abaseplate (2) to a front face of which the side wall (1) is fastened oron a rear of the side wall (1) itself, of said actions being directed inan approximately horizontal direction (Oy) parallel to, axes of therolls and being exerted via means for connecting each of the said thrustmembers to the said baseplate, characterized in that the said means forconnecting a first thrust member allow translational relative movementbetween the said thrust member and the baseplate (2) or the side wall(1) both in a horizontal direction (Ox) parallel to a plane of the planefaces of the rolls and in a vertical direction (Oz) parallel to theplane of the plane faces of the rolls, in that the said means forconnecting a second thrust member allow translational relative freemovement between the said thrust member and the baseplate (2) or theside wall (1) in a horizontal direction (Ox) parallel to the plane ofthe plane faces of the rolls and in that the said means for connectingthe third thrust member allow no translational relative movement betweenthe said thrust member and the baseplate (2) or the side wall (1). 2.Device according to claim 1, characterized in that the said means forconnecting a first thrust member consist of a ball joint (13) into whichis inserted a movable, rod (8) forming part of the said thrust member,said trust member also being fastened to the frame (3) by means of aball joint (12)3.
 3. Device according to claim 1, characterized in thatthe said means for connecting a second thrust member consist of aslideway (22) fastened to the baseplate (2) or the side wall (1) anddirected horizontally along the said horizontal direction (Ox), a rigidrod (20), one end of which is inserted into the said slideway (22) andthe other end of which is connected by a ball joint (21) to a rigid rod(17) forming part of the said second thrust member or being connected toit, the said rigid rod (17) passing through a slideway (19) directedalong the said horizontal direction (Oy) and allowing the said rigid rod(17) to move only along the said horizontal direction (Oy).
 4. Deviceaccording to claim 3, characterized in that the said means forconnecting the third thrust member consist of a ball joint (28) fastenedto the baseplate (2) or to the side wall (1) and a rigid rod (25)forming part of the said third thrust member or being connected to it,the said rigid rod (25) passing through a slideway (27) directed alongthe said horizontal direction (Oy) and allowing the said rigid rod (25)to move only along the said horizontal direction (Oy).
 5. Deviceaccording to claim 4, characterized in that the said second and thirdthrust members are connected to the said rigid rods (17, 25) via balljoints (18, 26).
 6. Device according to claim 4, characterized in thatthe said second and third thrust members are connected to the said frame(3) via ball joints (16,24).
 7. Device according to claim 1,characterized in that the first thrust member exerts its action on alower part of the baseplate (2) or of the side wall (1), while thesecond and third thrust members exert their actions on an upper part ofthe baseplate (2) or of the side wall (1).
 8. Device according to claim1, characterized in that the said thrust members are controlledcylinders (4, 5, 6).
 9. Device according to claim 8, characterized inthat the said cylinders (4, 5, 6) are connected to the said frame (3)via ball joints and spring-loaded devices allowing the correspondingcylinder to move backwards in the horizontal direction (Oy).